Step-by-step explanation:
You need to remember that
[tex] log( \frac{a}{b} ) = log(a) - log(b) [/tex]
and
[tex] log(ab) = log(a) + log(b) [/tex]
then the solution is
[tex] log( \frac{r}{st} ) = log(r) - log(st) \\ = log(r) - ( log(s) + log(t) ) \\ = log(r) - log(s) - log(t) [/tex]
